While sex (or gender) in higher vertebrates is determined at fertilization, sex determining genes in chicken become active at a later stage during embryogenesis to induce the formation of testes or ovaries. This has led to the long-standing belief that much of the underlying genetic pathway is conserved through the later stage of embryogenesis. However, comparative studies on sex determination in the chicken embryo have revealed both conserved and divergent elements in the pathway. For example, the gonads of chicken embryos are morphologically indistinguishable between the sexes, and thus “indifferent” or “bipotential,” at days 3.5-4.5.
In the poultry and other animal-production markets, including but not limited to chickens, turkeys, and the like, the ability to control or affect the sex of the animals would greatly enhance the production and efficiency of production. For example, in egg laying operations only hens or females are desired. Thus, when a flock of avian is born, only female avians are retained and often male avians are euthanized or otherwise disposed of. Because males and females are born at an approximate 50/50 sex ratio, approximately half of all avian born at such operations are thus lost and unproductive or provide diminished production.
A need thus exists for controlling, promoting, or otherwise influencing the sex of the avians before hatching in order to selectively produce more male or female avians, and thereby increase production and decrease waste and costs. A need also exist for robust cost effective lighting fixtures that can achieve such results.